A laser ignition is described in PCT Application No. WO 2005/066488 A1, for example.
The ignition laser has a combustion chamber window which transmits laser pulses emitted by the ignition laser. At the same time, the combustion chamber window has to withstand the high pressures and temperatures, prevailing in the combustion chamber, over the entire service life of the internal combustion engine, without the optical properties of the combustion chamber window being adversely influenced. At the surface of the combustion chamber window facing the combustion chamber, surface temperatures are able to occur, in this context, of more than 600° C. and pressures of more than 250 bar, during the power cycle of the internal combustion engine. In addition, chemically aggressive components of the exhaust gases are able to damage the combustion chamber window, and deposits on the combustion chamber window are able to reduce its transmissivity.